Lubricating oil



idize during use.

present-day hydrocarbon lubricants of the very UNITED STATES PATENT oFncE LUBRICATIN G OIL Bert H. Lincoln and Gordon D. Byrkit, Ponca City, Okla., assignors to Continental Oil Company, Ponca City, Okla., a corporation of Delaware No Drawing. Application November 27, 1940,

Serial No. 367,462

8 Claims. (01. 252-46) Our invention relates to lubricating oils and more particularly to improved lubricating oils of high film strength, high resistance to oxidation, and markedly reduced formation of come-- sive products during use.

This application is a continuation-in-part of our co-pending Serial No. 283,569, filed July 10, 1939.

Present-day mechanical devices require lubricating oils ofhigh film strength, of high oiliness characteristics, and of low tendency to ox- It has been found that the highest quality are deficient in these very important characteristics. These three properties are of vital importance under conditions of thin film lubrication where the lubricant has been squeezed from between the friction surfaces because of-high pressure, slow speeds, and other causes. In modern engines, large surfaces of oil' are exposed to the action of atmospheric oxygen, promoting rapid oxidation. It is readily seen that the viscosity or the body of the lubricant culating the lubricant, there is always a short period of time in which the rubbing surfaces must operate under conditions of dry friction if ordinary hydrocarbon lubricants are used. With dry friction, the wear on friction surfaces is extreme; and during cold weather when the lubricant is sluggish or during periods when the lubricating system, i not functioning properly for one reason or another, rubbing surfaces may not only suffer considerable wear but may be damaged to the point where they must be replaced. The product of our invention has a very important property of reaction with the metal surfaces, penetrating or absorbing on the metal surfaces, "and leaving a film of lubricant with high oiliness character, which remains on the metal surface irrespective of the length of time the machine has been idle.

' gineer.

plays no part in thin film lubrication and that the remaining film of oil must have a very high film strength and be of high oiliness value to prevent rupture of the film of the lubricant, which would cause seizure. tend to keep the coefficient of friction as low as possible. The oil must resist oxidationwhen these thin films are heated in the presence of atmospheric oxygen as they are in use.

Mechanical devices are being designed for higher pressure operation, and the film strength of the best quality straight hydrocarbon lubricant has been foundto be too low for satisfactory service. It will be obvious that an invention which provides a means of improving the film strength ofthese lubricants is of great importance to the art of lubricant manufacture and to the designer and fabricator of mechanical devices.

Substantially all machines operate in part or at times totally under conditions of boundary or thin film lubrication, under which conditions the oiliness or unctuosity of the lubricant is the first and primary requisite of efficient operation. Those skilled in the art of lubricant manufacture or machine manufacture will readily appreciate the value of, an invention that will improve the oiliness of these otherwise high-quality lubricants. Furthermore, sludge and acid are especially deleterious under conditions of thin film lubrication. The sludge is not a lubricant in any sense of the word, and the soluble acid is particularly corrosive to hearing metals such as cadmium-silver, copper-lead, and. the like.

In starting idle mechanical equipment which is lubricated from a sump by pumping or cir- The oil film must.

When the hydrocarbon lubricants are diluted with unburned fuel or with other light hydrocarbons, the small degree of oiliness of the original hydrocarbon lubricant is greatly decreased.

It is well known that, i order to obtain lubricants which are preeminently satisfactory from the standpoint of oxidatio in use, it is necessary, to refine the oil thoroughly and then to add an inhibitor of oxidation. The thorough refining may consist of many and heavy acid treatments or solvent treating so as to remove a considerable part of the oil and leave only the most stable portion. Such drastic refining is necessary in order to obtain stability with respect to sludge formation, but the oil is then subject to easy. oxidation to form soluble acids and other corrosive materials. This can be prevented by the addition to the refined oil of small amounts of materials which either prevent the formation of these corrosive products or by some action render them inert. Furthermore, such well-refined oils are susceptible to the formaor unstable. In introducing s the R's of our thiocarbonates, we do not use ad- I tion and thus avoid these dimculties by this.

lence, tend to produce regimentation of the molecules of hydrocarbon oil when added thereto. A

metal immersed in a strongly polar compound will show a film of the compound in which there is a regimentation of molecules oriented with respect to the surface of the metal by which they ar adsorbed or absorbed.

Many of our additive materials are efiective when added topoorly refined or even wholly unrefined lubricantsi The addends may thus be substituted in whole or in part for the usual refining processes.

In the prior art of applying these principles to the manufacture of lubricants, many diverse types of materials have been suggested to be added to obtain improvement in various characteristics. It has been found that the addition of various compounds frequently improves film strength, oxidation resistance, noncorrosiveness, and other characteristics.

One object of our invention is to provide-improved inhibitors of oxidation and corrosion for addition to lubricants.

Another object of our invention is to provide film strength improving. addition agents suitable for use in lubricants and especially in crankcase lubricants.

. Other and further objects of our invention ,will' appear in the course of'the, following description.

In general, our invention contemplates an oil. of lubricating viscosity having added thereto a small amount of an organic thiocarbonate ofthe general formula: RXC( :x XR' in which 0 represents carbon, X represents either oxygen or stil fur (at least one'of thexs must be sulfur) and -R. and R. are organic radicals one or both of which contains carbon, hydrogen, and sulfur.

The compounds here described and claimed contain extraordinarily high percentages of sulfur. Some of this sulfur is'in active form and some in inactive form. The use of these compounds in lubricants provides sulfur in various forms so that under any conditions sulfur is available for its beneficial action on lubricants and as an inhibitor of oxidation. In the above formula R and B. may be aliphatic, carbocyclic, or heterocyclic in character. It is to be understood that by thiocarbonate in the appended claims we mean to include mono and trithiocarbonates as well as the dithiocarbonates.

The introduction of this additional sulfur into our thiocarbonates permits of an extraordinary ness, or both; while another action is directed to the stability of the lubricant. For load-carrying capacity, quantities ranging from 0.1 per centto about '10 per cent may be added. As an anticorrosive agentior anti-siudgi'ng agent, or both, much smaller amounts may be required ranging from approximately 0.001 to 1.0 per cent. The action of our thiocarbonates is specific but difficult to understand. These compounds may be added to any type of hydrocarbon'lubricants but show an unusual value in highlyrefined and solvent-treated. lubricants. The blends prepared in accordance with the present invention are particularly suited for inhibiting corrosion of the new bearing metals such as cadmium-silver, copper-lead, and the like by suohoils.

By oil having lubricating'viscosity in the lippended claims. we means to include the so-called mineral oils and various, hydrogenated, polymerized and otherwise mi p ticallytreated oils such as voltolized oils, aluminum chloride treated oils, and the like. Furthermorggthelubricating oil may consist in whole or in fpart of shale oil,

animal or vegetable oils such as castor oil, lard oil, corn oil, cotton seed oil, and the like.

In practice, it, is better to employ compounds whose boiling point is above 225 degrees F. in order that the addition compound will not be evaporated or distilled in use. Tse selection or a particular compound or compounds to be used as an addition agent to the hydrocarbon or other oil is to be made considering the physical and chemical properties of the various compounds and the use to which the blend is put. if water is likely to be present during use, a substituted thiocarbonate is selected which is not aifected by water. If a particular added. compound proves too volatile for its application, a

higher boiling material should be used and the more volatile-compound used for blending. in an oil intended for duty at lower temperatures. In

general, for automotive crankcase lubricants, we I preferto use compounds having vapor pressures of less than atmospheric at 250 degrees F.

" The following compounds are the preferred embodiment of our invention. All and each of these are examples of our invention when blended in minor proportion in an oil of lubricating viscosity.

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flexibility in the design of the addend for a particular'purpose. Thus it permits the introduction of other types of sulfur if the sulfur in the thiocarbonate is insufllcient in amount or is too stable ulfur. groupings into ditional' thioc'arbonate groupings, since this is ot The particularthiocarbonates or this involvesincreased load-carrying ability oroiliinvention, have a dual action in a lubricant. one action Ldlihatict s w ercaptans 1. Mercapiocm lbutoxyethoxyathykantbate 2. Amylxanthy meroaptomethylstearate -b. Sulfides and polysuliides 3. Reaction product .0! sodium'laurylxanthate' with beta.

beta prime-dichloroothyl sulfide 4. Reaction product of sodium amyltrithiocarbonate with dichloroamyl trisuiiide c. Thioaoids and derivatives 5. Reaction productolsodium amylmonothiocarbonate with 7 methyl alphaohlorothiostoarate 0. Reaction product of lithium isobutylxautliate with nlphcbromotiiioyaleramide j d. Sultonea and sulioxidcs I 7. Reaction not of sodium ethoxyethylxanthate with ome oamylsullone 8. Reaction product of sodium hexylxanthate with omegachloroamylsuiioxide e. Sulfur-iced aiipliaticoompounds 9. Reaction product oipotassium hexylxanthate with sulfur mine-bearing methyl oleate. 10. Reaction product oi potassium ethylxanthate with sulfur 1 v chloride treated methyl iinole'ato 11. Reaction producgeiesotassium benzylxanthate with sullfg oiigiofldo methyl esters of soybean or com o II. Carbocyclic types a. Mercaptans and thiophenols l2. Mercapto-dodecahydro-diphenyl othylxanthate 13. Reaction product of potassium butyi-mono-thiocarbonate and o-c lorophenyl ethylmercaptan b. Sulfides and polysulfides 14. Reaction product of chlorobenzyldisulflde and potassium hexyltrithiocarbonate l5. Reaction product of sodium amyltrlthiocarbonate and chlorophenylethyl disulflde 16. Reaction product of sodium amyl-monothiocarbonate with chlorodiphenyltrisulflde 17. Reaction product of potassium amylxanthate with chlorodiphenylsulflde c. Thioacids and derivatives 18. Reaction product of sodium laurylxanthate with omegachlorothiotoluic acid 19. Reaction product of sodium benzylxanthato with alphabromothiobutyramide d. Sullones and sulfoxides 20. Reaction product of potassium octadecylxanthate with chlorodipheuylsulfone 21. Reaction product of potassium ethyltrithiocarbonate with chlorodlbenzylsulfone 22. Reaction product of sodium ethylmonothiocerbonate 1 with chlorodibeniylsnlioxide III. Heterocyclic types 23. Reaction product of chlorohydroxythiophene with sodium butoxyethylxanthate 24. Reaction product of potassium ethoxyethylxanthatc with chlorothianthrene The other members of the classes represented may be used within the scope of our invention.

The thiocarbonates have varying degrees of solubility in hydrocarbon and other oils. In some cases it is necessary to use a solvent for the compound or to form colloidal suspensions of the compound in oil. While some of these compounds have only limited solubility in hydrocarbon oils, it is to be remembered that because of their great eificiency extremely small amounts are often effective. Thus we have used as little as 0.001 per cent of some of these compounds, and it will be-seen that a diflicultly soluble material may dissolve to a suflioient extent to be satisfactory for our purpose. In general, more than 0.001 per cent of our addition agents are used; and we may add one, two, or even five per cent or more.

Furthermore, it is well known that different types of oils'have different capabilities of dissolving a given material. For some purposes therefore, we prefer paraflinic, for other purposes, asphaltic, and for still other purposes, naphthenic or mixed base lubricants. Another method of obtaining a satisfactory mixture of addition agent with the hydrocarbon oil is the use of a mutual solvent to bring the addend into solution. Alternatively, peptizing agents may be added to maintain the substituted thiocarbonate in permanent suspension.

Many of the more difficultly soluble materials are rendered more soluble by the'introduction of alkyl groups, particularly those containing four or more carbon atoms. The lsoamyl, octyl, lauryl, and octadecyl radicals and radicals from paraflin wax greatly increase the solubility of organic compounds in oil. One or more of such groups may be introduced as required.

It is sometimes advantageous to combine more than one of these compounds in a blend to obtain particular properties. We accomplish this by mixing two or more of these'compounds together andfblending the mixture with thehydrocarbon oil orby blending one in the hydrocarbon oil, blending the second into this mixture, and so on until the composition is complete. I The various thiocarbonates improve both th film strength and oxidation characteristics of the and these are markedly improved by our compounds. The ability to reduce friction is another feature contributed to lubricants by som of our compounds. I

It may be desirable to include in one and the same blend, in addition to the addends here described, other addends for specific purposes. Thus, we may add a pour point depressor such as a naphthalenechlor wax condensation product, a viscosity index improver such as certain resins or polymerized hydrocarbons, and sulfurorphosphorus-containing inhibitors, in addition to our thiocarbonates. Furthermore, various metallic compounds may be added to the blend without interfering with the action of our ingredients. Indeed, in some cases it is. advantageous to combine with our thiocarbonate compounds in a hydrocarbon oil blend such materials as calcium dichloro-stearate, chromium oleate, aluminum stearate, and other metallic soaps. Various halogenated oxygen-bearing ring or aliphatic compounds may be added, such as methyl dichloros'tearate, chlorodiphenylene oxide and the like.

Other examples of halogen and phosphoruscontaining organic compounds which we may use advantageously in conjunction with our thiocarbonates includechlorinated paraffin wax chlorinated diphenyl, chlorinated naphthalene, chlorinated diphenyl ether, dichloropropyl ether, epichlorohydrin, octadecyl trichloroacetal, chlorobutyrone, o-chloroacetaphenone, trichlorobenzophenone, dichlorostearic acid, calcium dichlorostearate, dichlorostearamide, o-chlorostearanilide, pentachlorophenyl.benzoate, a chlorinated wax-diphenyl condensation product containing residual chlorine, trichlorophenyl, trichlo'roaniiine, chlorophenylstearic acid, chlorobenzanilide, chic-- rophenyl phosphate, tricresyl phosphate, chlorophenyl phosphine, cresyl phosphite, phosphazine, phosphanilide, phosphazobenzene, phosphorus isothiocyanide, phosphoryl isothiocyanide and the like. 'In general, any halogen or phosphorus- I blended in gasoline and other petroleum fuels either directly or after being blended first in "a lubricating oil and then added to the fuel. Soap thickened mineral oils of all types ranging from those showin only a slight increase in viscosity greases, the usual soaps such as sodium stearate,

aluminum stearate, calcium soaps of beta fat,

and the like may be used to form the large part of the necessary soap. Various other thickening ingredients or materials for other purposes may be added. These include yarn, hair, graphite, glycerol, water, lampblack, mica, zinc dust, litharge, and the like. s

In making a lubricating gasoline. we blend 0.5 per cent of a blend of a substituted thiocarbonate in oil with gasoline. It is to be understood, however, that the hydrocarbon oil in the treated fuels may be of a viscosity of from about 35 seconds at F. S. S. U. to 350 seconds or more and the 99.5 per cent. In some cases the fuel may be I prepared without adding any hydrocarbon oil. The quantity of 'thiocarbonate in the final blended fuel may vary from 0.001 to 1.0 per cent or slightly more.

' It will be understood that certain features and sub-combinations may be employed without ref-- erence to other species or combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing'from the spirit of our invention. It is therefore to be understood that our invention is not to be limited to the details described.

Having thus described our invention, we claim: 1. A lubricant comprising a major proportion of oil of lubricating'viscosity and a minor pro-r portion'of an organic thiocarbonate ofthe formula RXCXR' in which at least one X represents sulfur and the other Xs represent oxygen and in which R and R. represent organic radicals at least one of whichcontains carbon, hydrogen and sulfur said sulfur'being present in the-form of a sulfide polysulflde, mercaptan, thio acid, sulfone, sulfoxide, or as a sulfurlzed organic radical prepared by treatment with elemental sulfur.

2. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of an organic thiocarbonateoof the formula nxcxn' in which at least one X represents sulfur and the other Xs represent oxygen and in which R and R" represent organic radicals containing carbon, hydrogen and sulfur said sulfur being pres- RSROR amount of oil blended with the thiocarbonate to form the fuel addend may vary between 0 and in whicsh R and R represent organic radicals at least one of which contains carbon, hydrogen and sulfur said sulfur being present in the form of a sulfide, polysulfide, mercaptan, thio acid, sulfone, sulfoxide, or as a sulfurized organic radical prepared by treatment with elemental sulfur.

4. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of an organic xanthate of the formula RSCOR' in which R and R represent organic radicals containing carbon, hydrogen and sulfur said sulfur being present in the form of a sulfide, polysulfide, mercaptan, thio acid, sulfone, sulfoxide, or as a sulfurized organic radical prepared by treatamentwith elemental sulfur.

5. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of the reaction product of potassium amylxanthate and chlorodiphenylsulfide.

6. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of the reaction product of sodium lauryl xanthate with beta, beta prime dichloroethyl sulfide.

'7. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of the reaction product of chlorobenzyl disulfide and potassium hexyltrihiocarbonate.

8. A lubricant comprising a major proportion of oil of lubricating viscosity and a minor proportion of an. organic thiocarbonate of the formula nxc s B in which at least one X represents sulfur and the 1 a other X's represent oxygen and in which R and R represent organic radicals, at least one of which contains carbon, hydrogen, and sulfur, said sulfur beingpresent in the form of a sulfide, polysulfide, mercaptan, thio acid, sulfone, suifoxide or as a sulfurized organic .radical'prepared by. treatment with -a suifurizing agent selected from the group consisting of elemental sulfur and a sulfur compound.

BERT H. LINCOLN. GORDON D.BYRKIT, 

